(I feel very silly but I just realized I never considered how Kaos perceives pleasure. Pain is a signal that she can ignore unless it gets worse, tickling Kaos has to react to with a delayed, nonautomatic response, but nice sensations...
Kaos gives off BDE [Big Daughter Engery], real little sister vibes, so she got lots of head pats as a kid, so she'd associate that and other head-touching like playing with her hair as good. Even as in her current chaos form she'd enjoy it, but more on a psychological level.
Maybe touching her back too? Like cause it's a show of trust? But just rubbing is enough, a back massage wouldn't have any muscles to target.
Probably nothing else really. Kaos likes physical contact in general, but mostly when she's the toucher rather than the touchee...Yes I know how that sounds, shut up.)